A mini-review on pyrazolines as fluorescent chemosensors for Fe³⁺

Pyrazoline derivatives exhibit potential application as sensitive and selective chemosensors for the recognition of Fe3+ ions. Their distinctive structure has both donating and accepting sites and is delineated by delocalized orbitals. Through intramolecular charge transfer (ICT), ligand-to-metal charge transfer (LMCT), chelation-enhanced quenching (CHEQ), and H-bond interactions, pyrazoline derivatives show remarkable chromogenic and fluorogenic capabilities. The pyrazoline sensors demonstrated excellent selectivity, low detection limit, and precise metal ion detection. This mini-review provides a guide for utilizing pyrazoline-based "On-Off" chemosensors to identify Fe3+ in diverse fields.